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United States Department of Agriculture

Agricultural Research Service

Research Project: Microbiological and Product Quality Consequences of Housing Laying Hens in Production Systems

Location: Egg Safety and Quality

Title: Microbiological impact of three commercial laying hen housing systems

Authors
item Jones, Deana
item Cox, Nelson
item Guard, Jean
item Cray, Paula
item Buhr, Richard
item Gast, Richard
item Abdo, Zaid
item Rigsby, Luanne
item Plumblee, Jodie
item Karcher, D. -
item Robinson, C. -
item Blatchford, R. -
item Makagon, M. -

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 14, 2014
Publication Date: N/A

Interpretive Summary: Laying hens for consumer eggs in the U.S. can be housed in a wide variety of housing systems. Some states have enacted or are considering legislation defining minimum hen housing requirements. Research has been conducted over the years to determine the impact of commercial egg production on egg safety. This research focused on conventional cage housing systems. The current study was part of a national, multidisciplinary study examining the many facets of commercial egg production as they are impacted by conventional cage, enriched colony cage, and cage-free aviary housing systems. Housing management practices have a direct impact on egg safety. In alternative housing systems, eggs laid on the floor (outside of the nest box) have higher microbial levels and greater exposure to Salmonella and Campylobacter. Higher levels of dust in the housing system result in greater numbers of aerobic bacteria on the surfaces of unwashed eggs. Scratch pads found in the enriched colony cage housing system had very high levels of aerobic bacteria, coliforms, and prevalence of Campylobacter. Additional research is needed to determine if changes in scratch pad design and materials could reduce the currently noted microbial levels. There were no differences in Salmonella prevalence associated with unwashed eggs produced in all three housing systems. No matter the housing system utilized for laying hens, egg safety is enhanced when management decisions promote limited interaction between the hens and the eggs produced.

Technical Abstract: Hen housing for commercial egg production continues to be a societal and regulatory concern. Controlled studies have examined various aspects of egg safety but a comprehensive assessment of commercial hen housing systems in the US has not been conducted. The current study is part of a holistic, multidisciplinary comparison of the diverse aspects of commercial conventional cage, enriched colony cage, and cage-free aviary housing systems and focuses on environmental and egg microbiology. Environmental swabs and egg shell pools were collected from all housing systems during four production periods. Total aerobes and coliforms were enumerated and the prevalence of Salmonella and Campylobacter spp. were determined. Environmental aerobic and coliform counts were highest for aviary drag swabs (7.5 and 4.0 log cfu/mL, respectively) and enriched colony cage scratch pad swabs (6.8 and 3.8 log cfu/mL, respectively). Aviary floor and system wire shell pools had the greatest levels of aerobic contamination for all egg shell pools (4.9 and 4.1 log cfu/mL, respectively). Hens from all housing systems were shedding Salmonella spp. (89-100% of manure belt scraper blade swabs). The dry belt litter removal processes for all housing systems appears to impact Campylobacter spp. detection (0-41 % of manure belt scraper blade swabs) considering detection was much higher for other environmental samples. Aviary forage area drag swabs were 100 % contaminated with Campylobacter spp., whereas enriched colony cage scratch pads had a 93 % positive rate. There were no differences in pathogen detection in the shell pools from the three housing systems. Results indicate hen management to encourage nest box use in alternative housing systems is important for egg safety. Additionally, current outcomes indicate the use of scratch pads in hen housing systems needs to be more thoroughly investigated for impact on hen health and egg safety.

Last Modified: 10/20/2014
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